Field
The disclosed concept pertains generally to three-phase electric power systems and, more particularly, to diagnosing polarities and phase associations of current sensors under different wiring configurations for electric power or energy meters or protective relays used in three-phase electric power systems.
Background Information
In electric power system metering and protective relaying applications, it is critical that current sensors be configured correctly. Incorrect configurations of current sensors often involve current sensors having reversed polarities or being associated with wrong phases. Such incorrect current sensor configurations lead to incorrect metered electric power and energy values, or malfunctions in protective relays.
A conventional approach for diagnosing current sensors' polarities and phase associations is based on three-phase sums of real, reactive or apparent power quantities. By collecting voltage and current measurements from three-phase electric power systems, the three-phase sums of real, reactive and apparent power quantities are either directly measured or calculated. Current sensors' polarities and phase associations are then determined based on the three-phase sums of real, reactive or apparent power quantities.
Different combinations of current sensors' polarities and phase associations may result in identical three-phase sums of real, reactive and apparent power quantities. Therefore, the conventional approach sometimes is unable to distinguish among such combinations.
Therefore, there is a need for a method or apparatus that can correctly and accurately diagnose current sensors' polarities and phase associations in different wiring configurations.